[PATCH v2 0/6] mm: Fix vmemmap optimization accounting and initialization

Muchun Song
2026-04-15T11:14:29Z

This patch series fixes a number of issues related to vmemmap optimization
for compound pages (e.g., DAX), including incorrect page accounting and
missing architecture-specific initialization steps.

The series addresses these issues through the following steps:
- Patch 1: Fixes a vmemmap accounting underflow in error paths.
- Patch 2-3: Fixes DAX vmemmap accounting by plumbing the pgmap
argument through memory deactivation paths.
- Patch 4-5: Fixes missing architecture-specific page table syncs by
plumbing the pgmap argument through vmemmap_populate APIs.
- Patch 6: Fixes pageblock migratetype initialization for large
compound ZONE_DEVICE pages.

Changelog:
v1 -> v2:
- Moved vmemmap accounting to populate_section_memmap() /
depopulate_section_memmap() to fix accounting underflow,
suggested by Mike.
- Replaced VM_BUG_ON with VM_WARN_ON_ONCE as requested by David.
- Reduced frequency of calling cond_resched() in pageblock_migratetype_init_range()
based on feedback from David and Mike.
- Extracted all bugfix patches from a larger patchset
(https://lore.kernel.org/linux-mm/20260405125240.2558577-1-songmuchun@bytedance.com/)
into this separate patchset, suggested by David.

Muchun Song (6):
mm/sparse-vmemmap: Fix vmemmap accounting underflow
mm/sparse-vmemmap: Pass @pgmap argument to memory deactivation paths
mm/sparse-vmemmap: Fix DAX vmemmap accounting with optimization
mm/sparse-vmemmap: Pass @pgmap argument to arch vmemmap_populate()
mm/sparse-vmemmap: Fix missing architecture-specific page table sync
mm/mm_init: Fix pageblock migratetype for ZONE_DEVICE compound pages

arch/arm64/mm/mmu.c | 11 +--
arch/loongarch/mm/init.c | 12 +--
arch/powerpc/include/asm/book3s/64/radix.h | 9 +--
arch/powerpc/mm/book3s64/radix_pgtable.c | 18 +++--
arch/powerpc/mm/init_64.c | 4 +-
arch/powerpc/mm/mem.c | 5 +-
arch/riscv/mm/init.c | 9 ++-
arch/s390/mm/init.c | 5 +-
arch/s390/mm/vmem.c | 2 +-
arch/sparc/mm/init_64.c | 5 +-
arch/x86/mm/init_64.c | 13 +--
include/linux/memory_hotplug.h | 8 +-
include/linux/mm.h | 8 +-
mm/hugetlb_vmemmap.c | 4 +-
mm/memory_hotplug.c | 12 +--
mm/memremap.c | 4 +-
mm/mm_init.c | 42 ++++++----
mm/sparse-vmemmap.c | 93 ++++++++++++++--------
18 files changed, 160 insertions(+), 104 deletions(-)

--
2.20.1